This application claims the benefit of the Korean Application Nos. P2001-58646 filed on Nov. 21, 2001, and P2002-2283 filed on Jan. 15, 2002, which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a cathode ray tube (CRT), and more particularly, to a funnel in a CRT, which can secure an adequate vacuum strength, and improve a deflection sensitivity, one of deflection yoke efficiencies, and a wedge insert ability.
2. Background of the Related Art
A related art CRT will be explained, with reference to FIGS. 1 and 2.
The related art CRT is provided with a panel 10 and a funnel 20 welded to rear of the panel 10 with frit glass. The panel 10 has flat or curved outside surface and inside surface, and the funnel 20 is a cone formed.
In the meantime, there is an electron gun 19 sealed in a rear part of the funnel 20 for emitting an electron beam, and there is a shadow mask 12 fitted with a gap to the inside surface of the panel 10 having a radius of curvature similar to the radius of curvature of the inside of the panel.
The shadow mask 12 is welded to the frame 14, and the frame 14 is fixed to stud pins 16 fixed to the panel 10 through springs 15. There is an inner shield 17 fixed to the frame 14 by fixing springs 13 for shielding an external magnetic field.
The funnel will be explained with reference to FIGS. 1-3.
The funnel 20 is welded to the panel 10, to form a seal line 31, and a height from the seal line 31 to an outside surface of the panel 10 is a height (OAH) of the panel 10.
The funnel 20 is provided with a body part 21, a cone part 22, and a neck part 23. A connection part of the body part to the cone part 22 is called a TOR (Top Of Round) 33, and a connection part of the cone part 22 to the neck part 23 is called a neck seal 37. There is a RL (Reference Line) 35, a center of the electron beam deflection in the cone part 22, and there is a deflection yoke 18 fitted to the cone part 22 for deflection of the electron beam.
Since the cone part 22 in the funnel 20 is relatively thin compared to other parts, it is required that the cone part 22 is made to reinforce a vacuum strength. Therefore, as shown in FIG. 3, the cone part 22 has a circular section for uniform distribution of stress.
In the meantime, the electron beam from the electron gun 19 is made to make a curvilinear motion in a screen direction by the deflection yoke 18 in the cone part 22. Of a long side direction, a short side direction, and a diagonal direction of a rectangular screen, the diagonal direction is the farthest from a center of the screen. Accordingly, the electron beam deflected to the diagonal direction is required to make a curvilinear motion that is curved the most. Since the long side direction and the short side direction have shorter distances to the screen, the electron beams in the long side direction or the short side direction makes a curvilinear motion that is curved less than the electron beam in the diagonal direction.
When the electron beam hits the cone part 22, a shadow phenomenon occurs in which the electron beam is shaded by an inside surface of cone part 22, so as not to be shown on the screen. Therefore, the cone part 22 has an outside form designed to have a curvature similar to an electron beam path in the diagonal direction.
In the meantime, in order to form a rectangular screen, it is required that the path 22b of the electron beam passing through the cone part 22 also has a form close to rectangle, resulting to occur invalid spaces 22a in the long side direction and the short side direction through which no electron beam passes.
Disadvantages of the related art CRT, a CRT having a circular cone part 22 section, will be explained.
First, the circular cone part 22 also requires a circular deflection yoke 18. This causes far distances from the deflection yoke 18 to the electron beam both in the long side direction and the short side direction, leading to weaken the force of a magnetic field of the deflection yoke 18 to the electron beam week. Therefore, it is necessary to apply a strong current to the deflection yoke 18 for forming a strong magnetic field, and this requires much power consumption.
Second, in the invalid spaces 22a in the long side direction and the short side direction, degrees of close contact of the deflection yoke 18 with the electron beam are poor, to drop deflection sensitivity of the electron beam even if the identical current is applied to the deflection yoke 18.
In the meantime, as environmentally friendly and low powered electric appliances are currently required, improvement of the deflection yoke, that has much power consumption, is essential even in the CRT. However, for fabrication of a low powered deflection yoke, improvement of the form of the cone part in the funnel is required beforehand. Eventually, a CRT having a section similar to the deflection path of the electron beam is suggested. However, the non-circular cone part requires making the vacuum strength thereof weaker than the circular cone part. Besides, the non-circular cone part requires taking the deflection sensitivity, and the wedge insert ability into account. That is, the CRT, particularly, the cone part of the funnel, requires a proper balance of the vacuum strength, the deflection sensitivity, and the wedge insert ability.
Accordingly, the invention is directed to a funnel in a CRT that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the invention is to provide a tunnel in a CRT which permits securing an adequate vacuum strength.
Another object of the invention is to provide a funnel CRT which has an excellent deflection sensitivity and a wedge insert ability.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the funnel in a CRT includes a body part welded to a panel, a cone part connected to the body part having a deflection yoke fitted thereto, and a neck part connected to the cone part having an electron gun sealed therein, wherein the cone part is formed such that xcex94Y/xcex94X={YD-(DD*sinxcex82)}/{XD-(DD*cosxcex82)} is greater than 4, where DD denotes a diagonal length, XD denotes a long axis length, YD denotes a short axis length, and xcex82 denotes a diagonal angle between the long axis and the short axis.
Preferably, the xcex94Y/xcex94X=4.0-5.5, and more preferably, the xcex94Y/xcex94X=4.0-5.0.
Preferably, a part starting from a part the body part and the cone part are connected to a distance toward the cone part is formed to satisfy the range of the xcex94Y/xcex94X. Preferably, the distance is approx. 20 mm.
The diagonal angle is the same with an angle the long axis and the short axis of the screen of the CRT form.
Centers of radiuses of curvatures of a corner of the cone part are on the same line.
In another aspect of the invention, there is provided a funnel in a CRT including a body part welded to a panel, a cone part connected to the body part having a deflection yoke fitted thereto, and a neck part connected to the cone part having an electron gun sealed therein, wherein the funnel is formed such that c/(a+d) is in a range of 0.26-0.37, where xe2x80x98cxe2x80x99 denotes a length of the cone part, xe2x80x98dxe2x80x99 denotes a length of the body part, xe2x80x98axe2x80x99 denotes a length from a deflection center line of an electron beam to a front end of the cone part in the cone part, and xe2x80x98bxe2x80x99 denotes a length from a deflection center line of an electron beam to a rear end of the cone part in the cone part. Preferably, the c/(a+d) is in a range of 0.30-0.35. Preferably, the funnel is formed such that a/b is in a range of 1.00-1.20.
Thus, the CRT with a non-circular cone part of the invention can provide good vacuum strength, deflection sensitivity, and wedge insert ability.
Thus, the CRT with a non-circular cone part of the present invention can provide good vacuum strength, deflection sensitivity, and wedge insert ability.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.